The Journal of neuroscience : the official journal of the Society for Neuroscience
May 11, 2016
Florence Campana, Ignacio Rebollo, Anne Urai et al.
Global information in vision is perceived faster and dominates conscious perception compared to local details, according to a test of the reverse hierarchy theory. Using novel hierarchical stimuli where global orientation is defined solely by local orientation, observers reported global properties faster than local ones. Magnetoencephalography data showed global information was decoded during early visual processing regardless of task demands. Spontaneous subjective reports were dominated by global information, and the frequency and speed of spontaneous global perception correlated with accuracy and speed in the global task, but not the local task. This provides empirical evidence that conscious percepts emerge preferentially at a global level, accounting for the dominance of global percepts and the feeling of visual richness.
The Journal of neuroscience : the official journal of the Society for Neuroscience
April 11, 2012
Giuseppe Pagnoni
Brain imaging data show that experienced Zen meditators, compared to non-meditators, exhibit less frequent high-activity states in the ventral posteromedial cortex (vPMC), a hub of the default mode network linked to spontaneous thought. During a simple attention-to-breathing task, the skewness of the fMRI signal in the vPMC differed significantly between groups, and this measure correlated with performance on a sustained-attention test outside the scanner. Functional connectivity between the vPMC and the right temporoparietal junction, a region involved in redirecting attention, also related to test performance. These patterns may reflect the interplay of mind-wandering, meta-awareness, and focused attention, offering a potential marker for attentional abilities and their disruption in clinical conditions.
The Journal of neuroscience : the official journal of the Society for Neuroscience
May 4, 2011
Cristina Marzano, Michele Ferrara, Federica Mauro et al.
Dream recall after awakening is linked to specific brain oscillations that differ between REM and NREM sleep. After REM sleep, higher frontal theta activity (5-7 Hz) predicts successful dream recall, mirroring the brain activity seen when encoding episodic memories while awake. After stage 2 NREM sleep, lower alpha activity (8-12 Hz) in the right temporal area predicts successful recall. These findings suggest that the neurophysiological mechanisms for encoding and recalling episodic memories may be consistent across different states of consciousness.
The Journal of neuroscience : the official journal of the Society for Neuroscience
May 14, 2008
Wulf Hevers, Stephen H Hadley, Hartmut Lüddens et al.
Ketamine, but not the related drug phencyclidine (PCP), enhances the activity of specific GABA(A) receptor subtypes (alpha6beta2delta and alpha6beta3delta) at anesthetic concentrations, directly activating them at higher concentrations. This effect was observed in oocyte expression systems and in cerebellar granule neurons from mice, and was absent in neurons from mice lacking the alpha6 or delta subunits. The findings suggest that ketamine's greater central nervous system depressant effects, compared to PCP, may arise from its selective modulation of these GABA(A) receptors, which are abundant in the cerebellum.
The Journal of neuroscience : the official journal of the Society for Neuroscience
July 1, 1999
G G Kinney, L O Wilkinson, K L Saywell et al.
Certain drugs, such as phencyclidine (PCP) and 8-OH-DPAT, disrupt prepulse inhibition (PPI) of the startle response in both Sprague Dawley and Wistar rats. However, apomorphine and amphetamine only disrupt PPI in Wistar rats, not in Sprague Dawley rats. This strain difference is specific to PPI, as apomorphine-induced hyperlocomotion, another measure of dopamine receptor activation, was similar in both strains. The findings suggest that the effects of dopamine receptor agonists on PPI can be dissociated from their effects on other behavioral models of dopamine activation.
The Journal of neuroscience : the official journal of the Society for Neuroscience
July 15, 1998
B Adams, B Moghaddam
PCP and its analog ketamine produce a behavioral syndrome that models some aspects of schizophrenia. Previously, the psychotomimetic and cognitive-impairing effects were attributed mainly to the corticolimbic dopamine system. This study measured dopamine and glutamate efflux in the prefrontal cortex and nucleus accumbens of rodents after PCP injection, using microdialysis. PCP increased both dopamine and glutamate levels. Dopamine remained elevated above baseline 2.5 hours after injection, yet locomotor activity returned to baseline in less than 2 hours, and working memory impairment (measured by a delayed alternation task) was only evident up to 60 minutes after injection.
The Journal of neuroscience : the official journal of the Society for Neuroscience
December 1, 1986
R G Sorensen, M P Blaustein
Phencyclidine (PCP) binds with high affinity to a specific receptor in rat brain membranes, which is likely a voltage-gated, noninactivating potassium channel. Several potassium channel blockers, including aminopyridines and tetraalkylamines, displace PCP from this binding site, supporting the hypothesis. A photolabile PCP analog, m-azido-PCP, binds reversibly to two classes of sites on rat brain synaptic membranes: a high-affinity site (dissociation constant 0.14 ± 0.01 µM) and a low-affinity site (255 ± 55 µM). The high-affinity site corresponds to the PCP receptor. The rank order of potency for displacing PCP from this site among aminopyridines is 4-AP ≈ 3,4-diAP > 2-AP ≫ 3-AP; among tetraalkylamines it is TBA > TEA ≫ TMA.